In California, in fact, in the whole country, a wine must contain at least 75% of the named grape variety to label that varietal on the bottle. This gives winemakers creative flexibility to blend in up to 25% of other grapes. The rule ensures the named grape dominates the wine’s character. States can set stricter requirements than the federal standards. Oregon, for example, requires 90% of a single variety wine to come from most named grape varieties.